Evaluating Climate Change Impacts on Cotton Phenology and Yield Under Full and Deficit Irrigation Conditions in an Extremely Arid Oasis

Sustaining cotton (Gossypium hirsutum L.) production under limited water availability and climate change in an extremely arid oasis is a key challenge for the stakeholders. This study was conducted to quantify the climate change impacts on cotton phenology and seed yield under full (638 mm) and deficit (478 mm) irrigation regimes in an extremely arid oasis in China. The Root Zone Water Quality (RZWQM2) model with the integration of six global circulation models (GCMs) under two representative concentration pathways (RCP 4.5 and 8.5) was used to determine the potential impacts of climate change on cotton for future periods (2022-2047, 2048-2073, and 2073-2099) compared to baseline (1975-2000). The results revealed that number of days to anthesis and maturity was expected to be reduced under RCP 4.5 and RCP 8.5 with full and deficit irrigation for future periods compared to baseline. However, this reduction was maximum under RCP 8.5 for 2074-2099 with full irrigation treatment. Seed cotton yield was also expected to decrease by 13-18% (RCP4.5) and 14-18% (RCP 8.5) with full irrigation, while decline in yield was 10-14% (RCP 4.5) and 11-19.6% (RCP 8.5) under deficit irrigation for future periods. The maximum decline in yield appeared with deficit irrigation under RCP 8.5 for 2074-2099. This reduction in seed cotton yield is primarily attributed to elevated temperature in the future climate. A 25% deficit of irrigation compared to normal irrigation has also ensured a reasonable seed yield in future climate, therefore it could be considered as an irrigation management strategy in future for cotton production in extremely arid regions. Findings of this study will provide a better guidance to cotton growers for applying deficit irrigation to sustain cotton production under changing climate with limited water availability in XUAR and other similar agro-climatic regions.